Background and Objectives:The assessment of clinical attachment level (CAL) represents the gold standard for diagnosing and monitoring periodontal disease. The aim of the present study was to evaluate the performance of the newly introduced cemento-enamel junction (CEJ) probe in detecting CAL, using CEJ as a fixed reference point, and to compare the CEJ probe with the Florida stent probe (FSP) as well as with a standard manual probe, University of North Carolina-15 (UNC-15).Materials and Methods:Three examiners recorded the probing attachment level in 384 sites in case group (chronic periodontitis), and in 176 sites, in control group (healthy periodontal status), using the three probes. Subjects included both the sexes and ranged from 35 to 45 years. The experimental design was structured to balance the intra- and inter-examiner consistency at the same site during the two visits.Results:CEJ probe showed higher intra-and inter-examiner consistency over both FSP and UNC-15 in both the case and control groups. Frequency distribution of differences of various magnitudes of repeated measurements ≤1 mm was in the higher range of 86.8% to 87.5% for CEJ probe. The FSP was more reproducible than UNC-15 in detecting relative attachment level (RAL).Interpretation and Conclusion:CEJ automated probe was found to have greatest potential for accuracy and consistency in detecting CAL than FSP and UNC-15. The automated probes appeared to be more reproducible than manual probes.
Purpose: The aim of the study is to determine stress distribution on preloaded implant-abutment screws in three different implant systems under simulated occlusal loads. Materials and methods:Three abutments to implant internal hex joint systems were simulated by using the 3-dimensional finite element analysis; (1) Nobel Biocare replace tapered (2) Uniti (3) Lifecare self-threaded tapered cement retained abutments. Thermal load and contact analysis were used to simulate preload resulting from the torque in implant screw joint assemblies. The simulated preload implants were then loaded with three static occlusal loads (10N horizontal; 35N vertical; 70N oblique) onto the crown into the implant complex.Results: Under preload and static occlusal forces, maximum Von-Mises stresses were concentrated at the lower portion of abutment for all systems. Maximum stresses were concentrated at lower threaded portion of abutment screw in Nobel Biocare, Uniti but in Lifecare system, stresses were concentrated at the middle threaded portion. Maximum stresses were concentrated at middle threaded portion of implant in Nobel Biocare, Uniti but at the upper threaded portion in Lifecare. Stresses increased under static occlusal forces in abutment screw in Nobel Biocare and Uniti but were more under oblique forces. In Lifecare stresses decreased under horizontal forces and increased in vertical and oblique forces. Conclusion:Although, an increase or decrease was demonstrated for the maximum calculated stress values in preloaded screws. After occlusal loads, these maximum stress values were well below the yield stress of abutment screw systems tested.
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